Re: patch: improve SLRU replacement algorithm

On Wed, Apr 4, 2012 at 4:34 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> Interesting. You've spoken at length how this hardly ever happens and
> so this can't have any performance effect. That was the reason for
> kicking out my patch addressing clog history, wasn't it?

Uh, no, the reason for kicking out your clog history patch was that it
caused throughput to drop by a factor of 3 on a pgbench test at scale
factor 300.  I assume you've got a bug there somewhere, or maybe
there's some other effect that hasn't been quantified.

> Why is this pgbench run accessing so much unhinted data that is > 1
> million transactions old? Do you believe those numbers? Looks weird.

Seems pretty normal to me, for the reasons Greg Stark states.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
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